Cut a thin slice off the top of each tomato. Scoop out pulp, leaving a 1/2-in. shell; invert onto paper towels to drain.,In a small bowl, combine the spinach, sour cream, cheddar cheese, onions and salt. Spoon about 1/2 cup into each tomato.,______,Bake, uncovered, at 350° until heated through, 40-45 minutes.